When we have friends who betray us, time does not always make us forget. The pain may go away, but the memories remain. Time does not change a loss of trust.
Also over time, good memories with good friends remain, despite the fact that we grow apart from those friends as our lives grow apart. It can be difficult adjusting to life without those good friends, but memories linger on.
Change is constant, and our memories help us to grow as individuals.